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SUMMARYA bacteriological study was made of blood specimens taken repeatedly during a 2-year period from a child with subacute bacterial endocarditis who received intensive treatment with antibiotics. The conventional bacillary form of Corynebacterium sp. was present in the blood and bone marrow of the patient before the beginning of antibiotic therapy and on occasions when the administration of antibiotics was suspended. These were the periods when the patient showed overt symptoms of clinical illness. When antibiotic therapy was adequate to produce clinical remission of symptoms, the infecting organism was not eradicated, but persisted in the blood in a small granule-like form that could be demonstrated and cultured only by highly specialized techniques. The cultural procedures required to bring about reversion of the granule-like form to the conventional bacillary form and the morphology of the various transitional forms that the organism assumed during the reversion process are described and illustrated.

B3ARILE, MICHAEL F. (National Institutes of Health, Bethesda, AMd.), WX ALTER F. iMALIZIA, AND DONALD B. RIGGS. Incidence and detection of pleuropneumonia-like organisms in cell cultures by fluorescent antibody and cultural procedures. J. Bacteriol. 84:130-136. 1962-A total of 102 tissue-cell cultures from 17 separate laboratories was examined for pleuropneumonia-like organisms (PPLO) by the fluorescent antibody and cultural procedures. PPLO were isolated from 48 of the 49 tissue-cell cultures found positive for PPLO by the fluorescent antibody l)rocedure, and results of the two procedures agreed in 101 of the 102 (99%) cases. PPLO were isolated from none of 10 primary-cell cultures prepared from six animal species and from 48 of 92 (52%) continuous-cell cultures prepared from eight animal species. Cells grown in media containing antibiotics were more frequently contaminated with PPLO (72%) than cells grown in antibiotic-free media (7 %). Cultures (91%) from tissue-cultureproducing laboratories and cultures (76%) used for propagation of microorganisms were contaminated with PPLO, although none used for tissueculture metabolic studies was contaminated. In addition, our findings support the view that PPLO contamination of cell cultures is probably owing to bacterial contaminants which revert to L forms in the presence of antibiotics. Continuous tissue-cell cultures are frequently contaminated with pleuropneunmonia-like organisms (PPLO) or L forms of bacteria or both